Context The novel influenza A(H1N1) pandemic affected Australia and New Zealand during the 2009 southern hemisphere winter. It caused an epidemic of critical illness and some patients developed severe acute respiratory distress syndrome (ARDS) and were treated with extracorporeal membrane oxygenation (ECMO). Objectives To describe the characteristics of all patients with 2009 influenza A(H1N1)associated ARDS treated with ECMO and to report incidence, resource utilization, and patient outcomes. Design, Setting, and Patients An observational study of all patients (n=68) with 2009 influenza A(H1N1)-associated ARDS treated with ECMO in 15 intensive care units (ICUs) in Australia and New Zealand between June 1 and August 31, 2009. Main Outcome Measures Incidence, clinical features, degree of pulmonary dysfunction, technical characteristics, duration of ECMO, complications, and survival.
Primary graft failure (PGF) is a devastating complication that occurs in the immediate postoperative period following heart transplantation. It manifests as severe ventricular dysfunction of the donor graft and carries significant mortality and morbidity. In the last decade, advances in pharmacological treatment and mechanical circulatory support have improved the outlook for heart transplant recipients who develop this complication. Despite these advances in treatment, PGF is still the leading cause of death in the first 30 days after transplantation. In today's climate of significant organ shortages and growing waiting lists, transplant units worldwide have increasingly utilised “marginal donors” to try and bridge the gap between “supply and demand.” One of the costs of this strategy has been an increased incidence of PGF. As the threat of PGF increases, the challenges of predicting and preventing its occurrence, as well as the identification of more effective treatment modalities, are vital areas of active research and development.
BackgroundWe recently reported that frailty is independently predictive of increased mortality in patients with advanced heart failure referred for heart transplantation (HTx). The aim of this study was to assess the impact of frailty on short-term outcomes after bridge-to-transplant ventricular assist device (BTT-VAD) implantation and/or HTx and to determine if frailty is reversible after these procedures.MethodsBetween August 2013 and August 2016, 100 of 126 consecutive patients underwent frailty assessment using Fried’s Frailty Phenotype before surgical intervention: 40 (21 nonfrail, 19 frail) BTT-VAD and 77 (60 nonfrail, 17 frail) HTx—including 17 of the 40 BTT-VAD supported patients. Postprocedural survival, intubation time, intensive care unit, and hospital length of stay were compared between frail and nonfrail groups. Twenty-six frail patients were reassessed at 2 months or longer postintervention.ResultsFrail patients had lower survival (63 ± 10% vs 94 ± 3% at 1 year, P = 0.012) and experienced significantly longer intensive care unit (11 vs 5 days, P = 0.002) and hospital (49 vs 25 days, P = 0.003) length of stay after surgical intervention compared with nonfrail patients. Twelve of 13 frail patients improved their frailty score after VAD (4.0 ± 0.8 to 1.4 ± 1.1, P < 0.001) and 12 of 13 frail patients improved their frailty score after HTx (3.2 ± 0.4 to 0.9 ± 0.9, P < 0.001). Handgrip strength and depression improved postintervention. Only a slight improvement in cognitive function was seen postintervention.ConclusionsFrail patients with advanced heart failure experience increased mortality and morbidity after surgical intervention with BTT-VAD or HTx. Among those who survive frailty is partly or completely reversible underscoring the importance of considering this factor as a dynamic not fixed entity.
Patients with very severe respiratory failure, which was considered to preclude conventional ventilation for safe transfer to tertiary centres, were managed by an ECMO referral and retrieval program in NSW and had a high rate of survival. This program also enhanced the capacity of the state to respond to a surge in demand for ECMO support due to the H1N1 epidemic, although the role of ECMO in respiratory failure is not yet well defined.
Overcoming bias due to confounding and missing data is challenging when analyzing observational data. Propensity scores are commonly used to account for the first problem and multiple imputation for the latter. Unfortunately, it is not known how best to proceed when both techniques are required. We investigate whether two different approaches to combining propensity scores and multiple imputation (Across and Within) lead to differences in the accuracy or precision of exposure effect estimates. Both approaches start by imputing missing values multiple times. Propensity scores are then estimated for each resulting dataset. Using the Across approach, the mean propensity score across imputations for each subject is used in a single subsequent analysis. Alternatively, the Within approach uses propensity scores individually to obtain exposure effect estimates in each imputation, which are combined to produce an overall estimate. These approaches were compared in a series of Monte Carlo simulations and applied to data from the British Society for Rheumatology Biologics Register. Results indicated that the Within approach produced unbiased estimates with appropriate confidence intervals, whereas the Across approach produced biased results and unrealistic confidence intervals. Researchers are encouraged to implement the Within approach when conducting propensity score analyses with incomplete data.
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